This invention relates to a composite aircraft cowl. It also relates to an aircraft cowl useful as a "transcowl" or the translating cowl component of a thrust reverser which advantageously utilizes the properties of composite materials in a simple design having few structural components.
The use of composite materials in many aircraft components has served to replace heavy metallic components with light weight equivalents which provide the same, if not greater, strength and/or stiffness. However, the substitution of composite materials for metals has generally taken place on a component by component basis; that is, a substitution for a metallic component is made with a composite component having the same basic geometry and required mechanical properties. The components must then be assembled in a manner analogous to the assembly of the metallic components. Such assembly is difficult and costly, requires complex fixturing, and often results in a structure which must be custom "trimmed" to fit together properly. Further, such fitting together of many components often supports and transfers stress in the manner intended for metallic components, rather than along the best stress support and transfer paths for composite components. For example, composite structures generally have laminated graphite/epoxy cloth layers over a honeycomb core. The graphite/epoxy layers have little resistance to interlaminar shear, but support tension along the direction of the fibers, while the honeycomb core supports compressive stresses perpendicular to the plane of the core, but is very poor in supporting shear in the plane of the core.
An additional disadvantage of fitting together a large number of components is that many fasteners must be used. This decreases the potential cost and weight advantages of using composites.
The above shortcoming of existing composite structures are especially evident in designs for transcowls. Some designs require assembly of up to four hundred separate structural components. Such designs often do not meet the expected weight criteria imposed as a design goal. Thus, aircraft weight and fuel consumption is increased.